/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.helpers;

import java.util.Date;
import java.text.FieldPosition;
import java.text.ParsePosition;
import java.text.DateFormat;

/**
 * Formats a {@link Date} by printing the number of milliseconds elapsed since
 * construction of the format. This is the fastest printing DateFormat in the
 * package.
 * 
 * @author Ceki G&uuml;lc&uuml;
 * @since 0.7.5
 */
public class RelativeTimeDateFormat extends DateFormat {
	private static final long serialVersionUID = 7055751607085611984L;

	protected final long startTime;

	public RelativeTimeDateFormat() {
		this.startTime = System.currentTimeMillis();
	}

	/**
	 * Appends to <code>sbuf</code> the number of milliseconds elapsed since the
	 * start of the application.
	 * 
	 * @since 0.7.5
	 */
	public StringBuffer format(Date date, StringBuffer sbuf,
			FieldPosition fieldPosition) {
		// System.err.println(":"+ date.getTime() + " - " + startTime);
		return sbuf.append((date.getTime() - startTime));
	}

	/**
	 * This method does not do anything but return <code>null</code>.
	 */
	public Date parse(java.lang.String s, ParsePosition pos) {
		return null;
	}
}
